The present invention relates to a check valve with pilot actuation for hydraulic systems.
Check valves having a pilot valve have been known in the art. In the known check valves the force required for opening a valve member of the pilot valve is relatively great. Reduction of the diameter of the seat for the valve member formed in the pilot valve has certain limits. The reason for this is that the diameter of a push rod moving the valve member from its seat because of the force acting thereon cannot fall below a certain dimension, since the push rod is relatively long and cylindrical. Furthermore, in the known check valves pressure-relief formations are provided in a main valve member so that the seat is located relatively far from the end face of the main valve member facing toward the push rod. Because of this, reduction of the length of the cylindrical portion is not possible. It is especially true since the reduction of the diameter of the cylindrical portion reduces resistance against bending with the third power and resistance against deflecting with the fourth power.